ZDP-189: Corrosion??

[JD Spydo]

One of my EDCs is my old trusty Caly Junior with the ZDP-189 blade. This is one of the older, original, first run Burgundy Caly Jr.s with the ZDP-189 blade steel.

I had a very surprising experience and not a good one either. I've been doing a lot of gardening this year growing fruits and vegetables. One evening I was slicing and processing some ripe tomatoes that I had grown and I was using my Caly Jr. ZDP to do it with. First of all I have never in the past had any abnormal corrosion problems with any of Spyderco's selection of blade steels.

But one particular evening I was cutting up and slicing some tomatoes and cucumbers and that evening I forgot to rinse my knife off with fresh water and wash it immediately as I normally do. The very next morning I was shocked: There were 3 distinct notches on the blade that appeared like I had been beating nails or some other metal objects with it. I immediately got out one of my jeweler's loupes to examine the notches. They were not done by force but they were done by unusually bad corrosion.

Now keep in mind I have processed many veggies on the past few years with Spyderco knives of all models and of many types of blade steel. But I had never, ever experienced that radical of corrosion on a blade in that short of time period.

I have 2 questions: Have any of you had any similar corrosion problems with ZDP-189 in particular?

Also have any of you noticed any corrosion that radical and that quick on any other selected blade steel that Spyderco uses?

[mrappraisit]

Wow, that stinks! I have used my ZDP Caly Jr to cut citrus tons of times, but always wash it afterwards, and it just has a very light patina. I have never heard of a case that bad, but tomatos are pretty acidic. Sorry to hear about that. And no, I have never heard of corrosion that severe and that quick. It's sounds like the perfect storm of corrosion.

[MAT888]

imo tomato/ juice is nasty .. it is not only acidic but also something else that will coat blades if not rinced of after work. Some flitz polish or other CrO compound chrome/metal polish and a micro fibre cloth should take care of your problem.

I have no ZDP one but hear more stuff about it staining easier as fe VG10 /S30V 440C . It has some more classic Carbon steel caracteristics i gues.. :cool:

[The Deacon]

JD, I use my ZDP Stretch II for food prep quite often and have never seen the slightest sign of corrosion. During the summer it sliced a number of tomatoes, often for my lunch at work. While it never went without cleaning overnight, it rarely got washed immediately either. Most days I'd just wipe it off with a damp paper towel, then wash it when I got home in the evening. I did manage to stain it by using it to spread mustard and letting it sit for a while. But that wasn't corrosion, it was more like a really bad job of cold bluing, and I've done the same thing to VG-10.

What you describe sounds almost more like electrolosis of some kind than simple corrosion. Where did the knife spend the night?

[tonydahose]

hey JD...where did this happen on the blade...on the zdp part or the the other metal that sandwiches the zdp (i forgot the name/number)

[LowTEC]

I have a pretty bad experience with my Kershaw Leek ZDP. I cut limes and lemons with it and left it unwashed over night :o , the next morning I found there are pits all along the edge . IMO the corrosion resistance of ZDP is hair better than CPMD2, and now I treat the ZDP as a tool steel and never have a problem ever since.

For your info, my VG-10 Yang has VERY light surface rust here and there over the blade, and I wash it every time after cutting veggie with it. A pass or 2 on buffing wheel fixed that.

I purposely leave my CPM S30V millie unwashed overnight after cutting lemons, and it doesn't have any sign of corrosion :) . Well, except the the screws and liners :p

[JD Spydo]

hey JD...where did this happen on the blade...on the zdp part or the the other metal that sandwiches the zdp (i forgot the name/number)

Tony the pits/notches were right on the very cutting edge of the blade. What baffles me more than anything is that there was no patina or staining on the face of the blade at all. There was no difference in appearance on the ZDP part of the blade than there was on the 420J2 part.
Deacon's guess of some sort of electrolysis is interesting but the knife lay on top of my wooden dresser that night. It was not laying on anything metal or any material that would create an electrolysis.

Under the loupe it looked as though some bug from outer space had literally taken small bites out of it. I talked to Spyderco and they asked me to send it to warranty and repair for them to look at. I think that's what I'm going to do. I'm just wondering if I got a bad batch of ZDP. I kind of doubt it though with Spyderco's quality control. But this is strange to say the least.

[Spider bite]

Can you post a pic of this?

[Slatts]

I left my Blue ZDP Delica out for a night after skinning several deer and it put on some rust in several spots. It was a little deeper than what I could get out with Flitz and buffing.

I think it's a bit much to expect to leave any knife blade exposed to the elements without some rust. But then again, I haven't tried H-1 yet.

[CombatGrappler]

I have used my Tom Krein reground ZDP Jess Horn to slice tomatoes, onions, and do some final chopping on lettuce. I gave it a thorough rinsing with tap water and dried it. It has never developed any pitting or staining.

Could you have had some type of small defect or crevice along the edge that held some of the acidic tomato juice and kept it from getting washed off?

[vivi]

I've used a ZDP Endura and Caly Jr frequently over the past two or three months without a single instance of corrosion, except for one. The Caly was deep in my pocket while I was quite active and was exposed to a lot of sweat. Near the edge where I had grinded away the polished side of the blade with an Extra Course DMT stone while reprofiling there was a small spot of brownish orange corrosion, but it wiped off. Other than that I've been pleasantly surprised with the corrosion resistance of the steel, after reading spotty reports from other members.

[JD Spydo]

Like I said earlier when I looked at the notches through a 17 power loupe it literally looked as though the malformations were truly the result of a type of corrosion. But it was a type of corrosion like I've never seen before in my life and I've worked around a lot of metal in my days.

What got me more than anything was the extremely short amount of time in which it happened. I've had knives with virtually every steel imaginable. I used the vast majority of different premium blade steels. But I have never seen the likes of this before on any knife blade.

I guess I was just wondering because of ZDP-189's very unique metallurgy if it had corrosion prone properties that are not common with other steels. Apparently I'm the only one thus far that this has happened to.

[StSumwhere]

I think it's a bit much to expect to leave any knife blade exposed to the elements without some rust. But then again, I haven't tried H-1 yet.

Sorry, but H1 is not impervious to rust.

Here's my Caspian after its first exposure to sea water.


I purposely left it unwashed over night to see what would happen. The rust occurred over the logos, but not exclusively over them. Also, this was the side up against the back of the sheath where the water was trapped against the blade.

[The Deacon]

That's definitely rust, but I'd be it's not the H-1 that has rusted. There have been a number of previous reports of simliar rust in the areas of the logos on H-1 knives. The general consensus is that it's the result of small particles of other steel that were deposited on the knife during the polishing process. You should be able to remove them with minimal effort and there should be no marks left on the knife afterward. In this case, the shape of them almost makes me wonder if they're from rivets in the sheath, or some other external source.

[JD Spydo]

That's definitely rust, but I'd be it's not the H-1 that has rusted. There have been a number of previous reports of simliar rust in the areas of the logos on H-1 knives. The general consensus is that it's the result of small particles of other steel that were deposited on the knife during the polishing process. You should be able to remove them with minimal effort and there should be no marks left on the knife afterward. In this case, the shape of them almost makes me wonder if they're from rivets in the sheath, or some other external source.

I agree with Deacon on his observation. That could have even happened by that blade just being in contact with another type of steel either in contact with or rubbing against it during corrosive conditions. I appreciate you calling our attention to your H-1 issue but I'd like to keep this thread on track discussing the possible corrosive properties or anamolies concerning ZDP-189 blade steel.

I still wonder that with the inordinately high amount of carbon in ZDP-189 that under certain conditions that it might be subjected to adnormal consequences such as the one I experienced. But apparently mine are unique so far. Good luck on your H-1 problem brother. Like Deacon says you can remove those stains with some high quality, non abrasive polish like Flitz

[v8r]

Tomatoes are very acidic ,when I was in the marching band in high school we used to polish symbols with ketchup,and it works very well.So I could see if tomato juice is left on steel very long it could cause it to rust.

[JD Spydo]

Tomatoes are very acidic ,when I was in the marching band in high school we used to polish symbols with ketchup,and it works very well.So I could see if tomato juice is left on steel very long it could cause it to rust.

Yeah I did realize that the tomatoes were high in acid and could be a potential corrosion problem. But I have still never had corrosion of this magnitude do this much in such a short time period.

I'm 90% sure that the unusually high carbon content in this particular steel makes it much more vulnerable than I had realized. It's probably going to be wise to treat ZDP-189 as though it is a carbon steel and not in the stainless arena.

But I do hope this serves as a preventative warning to those of you who use Spyders with ZDP-189 blades that it is prone to inordinate corrosion if not prevented.

[Hannibal Lecter]

My Dear Friend,

Sorry, but H1 is not impervious to rust.

Actually, it is. Deacon is exactly right - there might be rust present, but it is something else that is rusting, not the H-1.

--------
Hannibal

[SimpleIsGood229]

I've had a sort of odd experience with ZDP. As it went, I bought a ZDP Endura (tough knife when learning to sharpening lol) as my very first Spydie. With it's stock, almost-mirror finish, sweat would cause little specks of rust to appear. They came off easily, though.

After a while, I got very tired of the seemingly-1/4'' tick edge, so I sent it to Tom Krein for a FFG-regrind. It lost the near-mirror finish during the regrind. The grind lines are now very distict in comparison to the factory finish; you can feel them by running a fingernail over them crosswise. Now for the odd part: it doesn't rust nearly as easily now. I don't know why it doesn't rust as easily now, but I'm thankful for it!

[Murdoc]

I still wonder that with the inordinately high amount of carbon in ZDP-189 that under certain conditions that it might be subjected to adnormal consequences such as the one I experienced. But apparently mine are unique so far.

You're not alone, brother!

I've posted some pics of my E4 ZDP here, and these were made AFTER a good, thorough cleaning AND rubbing the **** out of this blade with various polish sponges etc.:

http://spyderco.com/forums/showpost.php ... ostcount=3

ZDP IS quite prone to pitting, at least in my pocket! :D